Long time ago now but my dd at that age felt more confident doing mince based dishes as easy to tell it was cooked properly (I'm veggie too, she's not. I've been veggie my whole adult life so not very confident cooking meat myself)
So:
Bolognese sauce
Chilli - can be used in tacos, enchiladas etc
Shepherds/cottage pie
Stovies
Also fish dishes:
Fish pie
Fish cakes
Breaded fresh fish - for "fish and chips" made at home - we (siblings and I) used to love helping gran on Fridays (catholic) making the fish for the fish suppers. Good quality fresh white fish (Cod or haddock are the most popular but there are loads of others we tended to have hake as grandpa liked it) one sibling did the flour coating, another the egg coating, another the breadcrumbs
Served with proper thick hand cut deep fried (in a chip pan not a safety fryer - oil had probably been in there for YEARS ) chips and mushy peas and if you were really lucky you'd get to "steal" a pickled egg off a grownups plate!
God that brings back memories!
Pizza is easy
Stews/casseroles are actually relatively easy - throw it all in, but maybe you do the herbs/spices as kids can tend to go overboard - dd always thought that a pinch of herbs wouldn't add much flavour and keep adding more and more 
What DD could make at 8/9 and what she would make at 12 onwards were very different
This is also very true!
@CherryPavlova totally agree children are more capable than they're allowed to be in Uk (generally speaking)
Totally normal for me for children of 8/9 upwards to help out in the kitchen including (safe, supervised) use of hot and sharp things.
But among dds peers (she's nearly 20) there were more than a few of them who weren't ALLOWED to boil a kettle or peel a vegetable at 17/18 unsupervised!
And these were healthy, able and neurotypical children/young adults absolutely no reason they couldn't have been managing in the kitchen
@AfterSchoolWorry no harder than finding the patience and time to teach them any life skill surely? And that's our job as parents - to teach them how to be capable, confident and able adults. If you buy pre-prepared stuff you actually have even less excuses
@MrsTerryPratchett why are you peeling garlic? If you use a crusher the peel is naturally left behind or if crushing manually a broad knife, place on garlic sharp side away and down and whack it down! Garlic crushed, peel separated